1. Field of the Invention
The present invention relates to a dual-slope light guide and a light source module and an optical assembly for a scanner, and more particularly to a light guide having a dual-slope reflecting surface, and a light source module and an optical assembly, using the light guide, for a scanner.
2. Related Art
Light-emitting diodes (LED) have the advantages of the high energy conversion efficiency, the power-saving property, the long lifetime and the small size, and have been widely applied to various light sources. For a scanner, a light beam emitted from the LED is point light, which needs to be converted by a light guide into linear light so that the illumination light beam required to scan an original can be provided.
The typical light guide has the object of guiding the light. The light guiding principle is to utilize the V-shaped grooves on the top surface to reflect or refract the light beams emitted from two ends to the top surface from which the light is to be outputted, so that the desired light beam is outputted from the top surface. This transversally extended and longitudinally arranged V-shaped grooves only can let the designer adjust the longitudinal light property of the light guide, but cannot let the designer adjust the transversal light property of the light guide. Thus, the increasingly stringent requirements or the diversified requirements, such as the response curve of the image sensor, cannot be satisfied.